Sugar transport is studied in a cultured epithelium formed by cells derived from pig kidney. Transport is assessed by measuring sodium dependent uptake of analogs of glucose into the epithelium as well as into apical membrane vesicles prepared from the epithelium. The number of apical membrane sodium-coupled glucose transporters is evaluated by measuring the specific binding of radiolabeled phlorizin. Growth of the epithelia in a medium containing high concentrations of glucose results in fewer apical membrane glucose transporters compared to growth in normal concentrations of glucose. When cell division is impaired following ionizing radiation, the increase in the number of apical membrane glucose transporters usually elicited by incubation in a low glucose medium is impaired. In contrast, ionizing radiation does not impair the loss of apical membrane glucose transporters seen when cells grown in a low glucose medium are switched to a medium containing a high concentration of glucose.